In triangle ABC AB = 2 cm, AC = 8 cm Cos A = 1/8. Find BC.

univerkov | March 27, 2021 | education

Let us find the side of the BC through the cosine theorem:

BC ^ 2 = AB ^ 2 + AC ^ 2 – 2 * (AB * AC) * cos A.

BC ^ 2 = 4 + 64 – 64 * cos 1/8 = 68 – 64 * cos 0.125 = 68 – 8 = 60 cm.

BC = 7.75 cm.

This variant of the problem always has a unique solution. To determine the length of the BC side, the cosine theorem is applied.

Answer: BC = 7.75 cm.

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